1. Field of the Invention
The present invention relates to a semiconductor package for three-dimensional mounting, a fabrication method thereof, and a semiconductor device. More specifically, the present invention relates to a semiconductor package for three-dimensional mounting which is easy to fabricate and has high packaging density, a fabrication method thereof, and a semiconductor device in which the semiconductor package for three-dimensional mounting is mounted onto a mother board.
2. Description of the Related Art
An example of a conventional BGA (i.e., ball grid array) type semiconductor package is illustrated in FIG. 15.
As illustrated in FIG. 15, a conventional BGA type semiconductor package includes a wiring substrate B and a semiconductor chip A placed on one surface of the wiring substrate B.
A first wiring pattern B2 is formed at the surface of the wiring substrate B on which the semiconductor chip A is placed, while a second wiring pattern B4 is formed at a surface of the wiring substrate B opposite the aforementioned surface. The first wiring pattern B2 and the second wiring pattern B4 are connected to each other via plated through holes B6 passing through the wiring substrate B.
The semiconductor chip A and the first wiring pattern B2 are connected to each other by wires D. A sealing resin layer C is formed at the surface of the wiring substrate B on which the semiconductor chip A is placed. The semiconductor chip A, the first wiring pattern B2, and the wires D are embedded in the sealing resin layer C.
On the other hand, the surface of the wiring substrate B on which the second wiring pattern B4 is provided is covered with a resist layer E formed by a photoresist resin. Openings E2 are provided at predetermined positions of the resist layer E, and the second wiring pattern B4 is exposed at the openings E2. Solder balls F are connected to the second wiring pattern B4 exposed at the openings E2.
When the above-described BGA type semiconductor package is mounted on a pad of a mother board via the solder balls F, a semiconductor circuit on the mother board is electrically connected to the semiconductor chip A via the pad, the solder balls F, the second wiring pattern B4, the plated through holes B6, the first wiring pattern B2, and the wires D.
However, the BGA type semiconductor packages are mounted onto a mother board only in a two-dimensional manner and cannot be stacked. Thus, there are limitations on the packaging density of the semiconductor packages which can be achieved on a mother board.
Use of small BGA type semiconductor packages can be considered as a means for increasing the packaging density of the BGA type semiconductor packages on the mother board. However, if the BGA type semiconductor packages are made compact, the pitch at which the solder balls are disposed is decreased. Therefore, mother boards manufactured by a buildup process or the like need to be used. As a result, a drawback arises in that mother boards are expensive.